How to log user_name in Rails?

Question

I use Devise in Rails 3. I want to see name of current_user in production.log.

I would like to configure rails like this:

config.log_tags = [:user_name]

Answer 1

I found this little tricky but working solution.

Warden stores user information in session, but req.session is not available for logging.

So you must add this to config/application.rb

config.middleware.delete(ActionDispatch::Cookies)
config.middleware.delete(ActionDispatch::Session::CookieStore)
config.middleware.insert_before(Rails::Rack::Logger, ActionDispatch::Session::CookieStore)
config.middleware.insert_before(ActionDispatch::Session::CookieStore, ActionDispatch::Cookies)

Then create file config/initializers/logging.rb

Rails.configuration.log_tags = [
  proc do |req|
    if req.session["warden.user.user.key"].nil?
      "Anonym"
    else
      "user_id:#{req.session["warden.user.user.key"][0][0]}"
    end
  end
]

Now I see this for Anonymous:

[Anonym] Served asset ...

and this for user:

[user_id:1] Served asset ...